Infective Endocarditis

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Introduction

  • A microbial infection of the endocardium and diseased heart valves (rheumatic heart disease, congenital heart disease, shunts, and prosthetic valves).
  • May be acute or sub-acute
  • Some acute cases occur in normal valves in intravenous drug users or may be part of systemic illness
  • Sub-acute form usually occurs on diseased valves
  • Causative organisms include: Streptococci, Staphylococci, Enterococci; Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella species ('Hacek' Organisms)

Clinical features

Acute:

  • High fever with rigors
  • Delirium
  • Shock
  • Development of new murmurs
  • Severe cardiac failure
  • Abscesses may form in many parts of the body (e.g. brain)

Subacute:

  • Low-grade fever
  • Signs of carditis
  • Finger clubbing
  • Arthralgia
  • Splenonegaly
  • Osler's nodules
  • Janeway lesions
  • Roth spots

Differential diagnoses

  • Myocarditis
  • Rheumatic heart disease

Complications

  • Cardiac failure
  • Destruction of heart valves
  • Systemic embolism (could be infective)

Investigations

  • Full Blood Count and differentials; ESR
  • Urinalysis; urine microscopy
  • Blood cultures X 3 (the yield is higher at the time of pyrexia)
  • Chest radiography
  • ECG
  • Echocardiography

Treatment goals

  • Stop the infection
  • Treat cardiac failure
  • Prevent coagulation disorders

Non-drug treatment

  • Bed rest
  • Low salt diet

Drug treatment

Initiate therapy (culture results awaited) with:

  • Benzylpenicillin 7.2 g daily by slow intravenous injection or intravenous infusion in 6 divided doses for 4 -6 weeks
    • May be increased up to 14.4 g daily if necessary (e.g. in endocarditis)

Plus:

  • Gentamicin 60 - 80 mg intravenously 12 hourly for 2 weeks

Following bacteriological confirmation institute appropriate antimicrobial therapy

Staphylococci:

  • Flucloxacillin: 250 mg - 2 g intravenously every 6 hours for 4 - 6 weeks
  • Vancomycin: 1 gm intravenously 12 hourly; Gentamicin 60-80 mg intravenously 12 hourly for 2 weeks

Enterococci:

Amoxicillin 2 gm intravenously 4 hourly; intravenously Gentamicin 60-80 mg 12 hourly

Candida:

   Systemic antifungals

  •       Amphotericin B: 8 - 1 mg/kg/day IV for at least 6 weeks

Plus

  •       Flucytocine: 25 mg/kg/day in 6 hourly

Notable adverse drug reactions, contraindications and caution

  • Penicillin: rashes, anaphylaxis
  • Gentamicin: nephropathy
  • Monitor patients on gentamicin and vancomycin carefully

Prevention

Prophylactic antibiotics for patients at risk who are undergoing:

Dental procedures. Under local or no anaesthesia, for those who have NOT had endocarditis, and have NOT received more than a single dose of penicillin in the last one month:

Amoxicillin

Adult: 3g orally 1 hour before procedure

Child under 5 years:  750 mg orally 1 hour before procedure;

5- 10 years: 1.5 g

For penicillin-allergic patients or patients who have received more than a single dose of a penicillin in the previous one month:

Azithromycin

Adult: 500 mg orally one hour before procedure

Child under 5 years: 200 mg orally;

5 - 10 years: 300 mg

Patients who have had endocarditis:

Amoxicillin plus gentamicin intravenously as for procedures under general anaesthesia (see below)

Dental procedures under general anaesthesia, and no special risk:

Amoxicillin

Adult: 1 g intravenously at induction of anaesthesia; additional dose orally 6 hours later 

Child under 5 years: a quarter of adult dose;

5 - 10 years half adult dose

Or:

Adult: 3g orally 4 hours before induction, then 3g as soon as possible after the procedure

Child under 5 years: a quarter of adult dose;

5 – 10 years old half adult dose

Special risk, e.g. previous infective endocarditis, or patients with prosthetic valves:

Amoxicillin plus gentamicin intravenously

Adult: 1 g amoxicillin plus 120 mg gentamicin at induction

Then oral amoxicillin 500 mg 6 hours after procedure

Child under 5 years: a quarter of adult dose 

plus 2 mg/kg gentamicin intravenously at induction

5 - 10 years: half adult dose for amoxicillin; 2 mg/kg gentamicin

Patients who are penicillin-allergic or have received more than a single dose of a penicillin in the last one month:

Vancomycin

Adult: 1g intravenously over at least 100minutes

Child under 10 years: Vancomycin 20 mg/kg

Plus

Gentamicin

Adult: 120 mg intravenously - Given at induction or 15 minutes before procedure

Child under 10 years: Gentamicin 2 mg/kg

Genito-urinary tract manipulation

As for special risk patients undergoing dental procedures under general anaesthesia

Obstetrics, gynaecological and gastrointestinal procedures

As for genitourinary tract manipulation